Fuel injection device



July 9, 1935.

Filed June 6, 1932 I INVENTOR Zam- O/af fleok/o m ATTORNEYS July 9, 1935. 1.. o. HEDBLOM FUEL INJECTION DEVICE Filed June a; 1932 2 Sheecs-Sheet 2 INVENTOR In! LRAM M Zens 0/0) l/edb/arq ATTO RNEYS STATES PATENT FUEL INJEUTION DEVICE Lars 0110i Hedblom, Detroit,

one-hall to Gustav A.

Mich, assignmof Carlson, Detroit, Mich.

Application June 6, 1932, Serial No. 615,624

3 @Dlaims.

The present invention pertains to a novel fuel injection pump designed particularly for the injection of fuel into the cylinder of a Diesel engine, although it is equally-useful for similar or related purposes.

The injection pressure stroke on the fuel-charge is derived from a cam shaft, and in this connection, the principal object of the invention is to lubricate the operating parts associated with this shaft and also to prevent leakage of fuel into the housing containing. the shaft and these parts. With this object in view, the cam shaft is enclosed in a fluid tight casing, and a circulation of lubricating oil is maintained through this casing, the path including a chamber dis-- posed between the casing and the point where the injection stroke is applied to the fuel charge. Thus, two pumping systems are provided, and these are constructed in such a manner that the pressure in the lubricating oil system is greater than that in the fuel system. Inasmuch as the oil circulation system passes between the afore mentioned casing and the point where pressure is applied to the fuel charge, there is no possibility of leakage of fuel from this point to the casing.

The cam shaft is operatively connected to the crank shaft of the engine, and in this connection, another object of the invention is to avoid operative performance of the cam-operated pumping mechanism when the engine is running on momentum after the throttling has been closed. To this end, the closing of the throttle eflects an adjustment in the pumping mechanism whereby continued rotation of the cam shaft under momentum results in no appreciable pumping action.

The invention is fully disclosed by way of example in the following description and in the accompanying drawings, in which- Figure 1 is a vertical section of the device;

Fig. 2 is a vertical section in a plane at right angles to the plane of Figure 1;

Fig. 3 is a detail section of a modified construction; and

Fig. 4 is a diagrammatic view illustrating the operation of the device.

Reference to the views will now be made by useof like characters which are employed to designate corresponding parts throughout.

The body or housing of the device comprises a crank case I upon which is mounted an upper pody portion 2 secured in position by any suitable means such as studs 3. To one of the sides of the crankcase I is secured a housing 4 for a turbine pump, and after assembly of the pump in the manner presently to be described, the housing A is closed by a lateral cover plate 5. A cam shaft ii is passed through the case I and is accommodated in roller bearings i mounted in the sides of the case. Within the case, the shaft 6 is formed with a cam 8 which serves a purpose presently to be described. The shaft 6 is extended as at 9 into the turbine housing a and is there equipped with a bladed rotor it slidably mounted by means of a pin it extending from the hub of the rotor into a slot H2 in the shaft extension 9. A spring I3 surrounding the hub of the rotor bears against the plate 5 urges the rotor against a packing It and an interposed thrust bearing 05. A fuel line it extends from a suitable source of supply to the interior of the turbine housing 4, and the fuel pumped by the turbine is ultimately delivered and injected into a cylinder.

in the upper part of the section 2 is formed a fuel reservoir IT. A sleeve I8 is passed through thetop of the section 2 and through the reservoir I! to extend a considerable distance towards the crank case I as may be seen in Figures 1 and 2. A delivery line I9 extends from the periphery of the turbine housing 4 to the reservoir ill.

The upper end of the reservoir I1 is sealed by a ring clamped by a nut 2| on the exposed portion of the sleeve I8. From the upper end of the sleeve extends a line 22 held by a coupling 23 and leading to an injection nozzle at the cylinder of a Diesel engine in a manner well known in the art and therefore not illustrated here.

A journal shaft 24 is mounted in the bottom of the crank case I in parallel relation to the shaft 6, and on the shaft 24 is journaled a curved rocker arm 25 in the form of a frame having its sides straddling the cam 8 in the manner illustrated in Figure 1. The rocker arm carries a roller 26 engageable with the cam 8, and in the normal position shown in Figure 2, the centers of the shaft 6 and roller 26 are preferably in the same horizontal line. The upper end of the rocker arm 25 carries another roller 21, the, center of which is normally in a. vertical line with the center of the shaft 6.

A horizontal shaft 28- is passed through one of the upper comers of the crank case I in parallel relation to the shaft 6 and carries a disk 29 to which is pivotallyattached a controlor operating arm}! at an eccentric point 3|. The arm 30 hasl'a straight lower edge 32 resting upon the roller 2'! and continued downwardly at.32' towards the free extremity of the arm.

On the lower end of the sleeve I8 is screwed another sleeve 33 having a flange 34 bearing upwardly against a shoulder 35 formed in the section 2. A plunger 35 is slidably mounted in the lower part of the sleeve 33 and extends upwardly through the sleeve |3 beyond the bottom of the reservoir l1. The lower end of the plunger 33 is rounded at 31 andrests upon the arm 33. The lower end of the plunger is further formed with a spring seat 33 receiving the lower end of a spring 33 which has its upper end bearing against the shoulder 34 to hold the plunger normally in engagement with the arm 33.

At the shoulder 34, ports 43 are drilled through the sleeve 33 and communicate with a chamber 4| formed in the upper section 2. An oil delivery line 42 extends to this chamber preferably from the crank case I. An oil outlet line 43 also extends from the chamber, returning to the crank case. Beneath the lower end of the sleeve l3, the plunger 35 is formed with an upwardly facing shoulder 44 which constitutes a piston area in drawing oil from the line 42 and discharging it into the line 43 when the plunger oscillates in the manner presently to be described. This pumping unit is made operative by the provision of a check valve 45 in the line 42 and opening in the direction of the chamber 4|, and another check valve 43 in the line 43 and opening in the direction of the crank case I. The valve 45 is backed by a spring 41 adjustable by means of a screw plug 43, whereby the pressure developed in the chamber 43 may be regulated.

In the upper end of the plunger 33 is formeda cavity 49 in which is mounted an upwardly opening poppet valve 53 resting on a spring 5|. Ports 52 are drilled through the sleeve l3 at the reservoir H to register with ports 53 in the plunger 33 and communicating with the cavity 43 when the plunger is in the lowered position shown in Figures 1 and 2. v

A plug 54 is mounted in the sleeve I3 at a distance above the upper end of the plunger 35 and has a series of passages 55 drilled therethrough. A poppet valve 55 is slidably mounted in the plug and is adapted to obstruct the passages 55 when in lowered position. A spring 51'bearing upon this valve normally holds it in closed position.

An arm 53 is secured to an end of the shaft 23 exteriorly of the crank case I andis suitably linked to the throttle of the engine. A spring 59 secured to an inner wall of the casing and bearing againsta pin 33 across the rocker arm 25 holds the roller 23 in constant engagement with the cam 3. When the throttle is closed, the arm 53 and pivot point 3| assume the position shown in Figure 2 and in full lines in Figure 4, and at this time the roller 21 does not ride beyond the straight edge 32. The center of the journal shaft 24 is displaced about three degrees from the vertical center line of the cam shaft 3, and this relation results in a negligible vertical lift in the arc of the roller 21, so that the plunger33 is practi cally stationary after the throttle has been closed. Thus, the turning of the cam shaft 3 under momentum after closing of the throttle causes no significant pumping and injection action although the rocker arm 25 may oscillate a few strokes.

As the, throttle is opened, the arm 53 apprpaches the dotted line position of Figure 4, retracting the pivot point 3| from the axis of the plunger 33-so that'the inclined edge 32" of the arm 33 comes into the path of the oscillating roller 21. Consequently, the arm 33 and hence the plunger 33 are osciilated. i

The function of the turbine pump I3 is merely to maintain the reservoir l1 filled with fuel oil. An overflow line 3| therefore extends from the reservoir in order to avoid the development of a substantial fluid pressure therein. A transparent sight tube may be inserted in the line 3| so that the flow of oil therethrough may be seen, and the stopping of this flow indcates depletion of the fuel source or some other defect in the mechanism. On replenishment of the fuel supply after depletion, the chamber I1 and connected lines may contain air, and this air may be expelled through a petcock (not shown) inserted in the line 5|.

In the fuel pumping operation of the device, the cavity 43 and the space between the plunger 33 and the plug 54 are filled with fuel from the reservoir |1 through the ports 52 and 53. On the upward movement of the plunger, the ports 53 pass out of register with the ports 52, thereby trapping in. charge of fuel within the sleeve ll. Continued upward movement ejects this charge of oil through the passages 55, Or the head of the valve 53 engages the stem 32 of the valve 53 and opens the latter. Atthis time, the valve 53 closes against the upper end of the plunger 33, since the spring 51 is preferably stronger than the spring 5|. Thus, a charge of fuel is forcibly injected into the line 22 and hence through the nozzle at the cylinder on each revolution of the shaft 5 which is geared to and properly timed with the crank shaft of the engine.

As previously stated, the shoulder 44 of the plunger 33 functions as a piston in a pumping unit embodying also the chamber 4| and the lines 42 and 43. An oil supply line 33 extends into the bottom of the crank case from a suitable supply adapted to maintain a constant level of oil within the crank case. The area of the shoulder 44 is greater than the total area of the upper end of the plunger 33, so that the pressure of lubricating oil developed in the chamber 4| is greater than that developed in the fuel pumping mechanism, whereby the downward leakage from the reservoir ll of fuel oil towards the crank case is effectively and positively prevented. At the same time, the lubricating oil circulating to the chamber 4| and ports 43 lubricates the contacting surfaces of the plunger 33 and sleeve 33 as well as the contacting surfaces of the end 31, arm 33 and roller 21.

In Figure 3 is illustrated a somewhat modified fuel pumping construction.

A sleeve I3 is passed downwardly into the upper section 2' in substantially the manner previously described and is further locked thereto by a nut 55 bearing upon a shoulder ,33 in the section 2. A sleeve 33' hangs from a shoulder 31 on the lower part of the sleeve I3 and is drawn upwardly against the shoulder 33 by the nut 35. The plunger 33' has two diameters to fit respectively in the sleeves I 3' and 33' and to provide clearance 33 in the sleeve 33 for the oil pumping action. In this case, however, the sleeve'33 is formed with ports 33 leading to a cavity 13 in the lower part of the section 2' so that the lubricating oil is returned directly to the crank-case rather than through an outside line such as the line 43 of Figure 1. The member 33' has a pressed fit into the member 2-, and the member I3 is similarly fitted into the sleeve 33'.

In either embodiment the position of the pivot point 3| is adjusted automatically in accordance with throttle adjustment, and hence there is an automatic adiustment in the length of the arm stepped plunger having a part reciprocable inplunger is automatically advanced and retarded in keeping with throttle adjustment. It will also be seen that the speed of the plunger is always high in comparison with that of the shaft 6 due to the ratio of more than 2 to l in the lever arms comprised in the rocker 25.

It will be understood that the unit illustrated and described herein serves one cylinder of a Diesel engine, and where a plurality of cylinders are provided, it is necessary to provide a corresponding number of units. These units may be built in multiple, and the respective operating cams thereof must be adjusted to operate in proper timed relation with the intended injection interval in each cylinder.

Although specific embodiments of the invention have been illustrated and described, it will be understood that various alterations in the details of construction may be made without departing from the scope of the invention, as indicated by the appended claims,

What I claim is:-

1. In combination, a fuel injector housing having two opposed coaxial walled cylinders 'having a common cylinder head, a hollow insert extending through said cylindersand through said head and having a shoulder thereon for pressure contact with the interior of the head in one of said cylinders, means threaded on each end of said insert for closing the open ends of said cylinders, said insert being of smaller diameter than either of said cylinders and defining two reservoirs therewith, one of said reservoirs having a fuel inlet thereto, the other of said reservoirs having a valvedlubricant inlet and outlet, a

said hollow insert, and a part 'reciprocable in one of said means, a walled passageway leading from the lubricant reservoir into the means which receives the said part of the plunger above the step of said plunger, a second walled passageway leading from the fuel reservoir to the interior. of said insert and to the interior of said plunger near the top end thereof, a valved outlet from the interior of said plunger, and a valved outlet from said insert above said plunger.

2. A fuel injector housing having a vertical cylindrical bore intermediate the length thereof terminating at each end in coaxial bores of larger diameter, a hollow insert coaxially of said bores having a shoulder thereon for contact with the base of the upper of said bores and threaded at each end, a hollow nut threaded on each end of said insert and bearing against the upper and lower edges of said upper and lower bores respectively, said insert being of smaller diameter than said upper and lower bores and defining reservoirs therewith, said insert and the lower nut comprising a stepped cylinder for a stepped plunger, said plunger having a valved reservoir therein in communication with the top one of said reservoirs and openings through the lower nut from the lower one of said reservoirs to the step of the plunger, a valved outlet from the insert above said valved reservoir, pressure means for feeding fuel to the top one of said reservoirs,

and valved lubricant inlet and outlet means for the lower of said reservoirs.

3. A fuel injector housing having a vertical bore intermediate the end thereof opening into an upper and a lower bore of larger diameter, a hollow cylindrical insert having a shoulder intermediate the length thereof for contact with the base of said upper bore, hollow nuts threadable onto each end of said insert for pressure contact with the upper and lower edges of said upper and lower bores respectively, said nuts also imposing pressure contact between the shoulder of said insert and the base of said upper bore, said insert with said upper bore and the nut on the lower end thereof defining two reservoirs, a stepped plunger having a part re ceived in said insert with the stepped part thereof received in the lower nut and comprising a pump for the lower one of said reservoirs, said plunger being hollow and having a valved outlet from the end thereof, walled passageways leading from the upper of said reservoirs into the hollow end of said plunger at a point substantially inwardly of thevalved end thereof, and

a valved outlet carried by said insert outwardly of the end of said plunger.

LARS OLOF HEDBLOM. 

